Generally, a drop-on-demand inkjet printing apparatus has an inkjet printhead that is used to eject fine droplets of printing ink for printing an image on a printing medium such as, for example, a printing paper. The inkjet printing apparatus is capable of printing an image having one or more predetermined colors on a surface of the printing paper. The inkjet printhead can use various ink ejection methods such as an electrostatic driving method, a thermal driving method, or a piezoelectric driving method, for example.
The inkjet printhead includes multiple ink chambers containing ink and multiple nozzles for ejecting the ink. The multiple ink chambers and the multiple nozzles can be arranged in one or more rows. The inkjet printhead can include a driving unit and a driving circuit. The driving unit can be any of the following examples: an electrode configured to apply an electrostatic force, a heater configured to heat ink and produce ink bubbles, or a piezoelectric actuator. The driving circuit can be configured to control the operation of the driving unit.
In some instances, the ink droplets may not be ejected through one or more of the nozzles for various reasons such as blocking of a nozzle, damage to the driving unit, and/or damage to the driving circuit. As a result, one or more nozzles can be unavailable during printing and having a nozzle or nozzles missing can reduce the quality of the image printed on the printing paper. For example, when a nozzle is unavailable or missing during printing for any one of the reasons described above, an inkjet printhead having substantially the same width as a printing paper such that the inkjet printhead can print an image on the printing paper without the inkjet printhead having to scan back and forth across the width of the printing paper, white bands corresponding to the missing nozzles are typically present on the printed image.